Search found 673 matches

by DMA
21 Jul 2016, 18:24
Forum: Keyboards
Topic: IDENTIFY THE KEYBOARD thread
Replies: 4190
Views: 307924

Anyone knows what this is?
Doesn't look like IBM - font is different. But what is it?
by DMA
21 Jul 2016, 02:20
Forum: Workshop
Topic: hbar beta, aka hbar's first adventure into Topre land
Replies: 25
Views: 2746

Since there is no resistor in the design, the rise time is only affected by the slew rate of the controller output and the bandwidth of the amplifier, which are both in the µs ballpark. But wouldn't voltage on TIA output drop to zero once voltage stops rising? I mean, wouldn't measure window be ver...
by DMA
20 Jul 2016, 17:07
Forum: Workshop
Topic: hbar beta, aka hbar's first adventure into Topre land
Replies: 25
Views: 2746

How do you get those 2us steps on the input from the stable excitation level?
by DMA
19 Jul 2016, 17:06
Forum: Workshop
Topic: hbar beta, aka hbar's first adventure into Topre land
Replies: 25
Views: 2746

The excitation is a rectangle. Since the integrating TIA measures charge, you don't see the spikes typical of the RC circuits you and others (xwhatsit etc.) use. The limited skew rate is probably due to the extra resistor I installed for my tests in an attempt at combatting 50Hz interference. I'll ...
by DMA
19 Jul 2016, 17:01
Forum: Workshop
Topic: [Done] CommonSense: matrix LCR meter with a HID interface
Replies: 569
Views: 62785

https://deskthority.net/workshop-f7/alternate-ways-of-sensing-teh-fs-t12533.html My scope pictures. I used the exact same board too... when the dev board is cheaper than the IC then the dev-board becomes your pcb ;-) You are miles ahead of where I got - keep on keeping on! I actually stopped right ...
by DMA
19 Jul 2016, 08:02
Forum: Workshop
Topic: hbar beta, aka hbar's first adventure into Topre land
Replies: 25
Views: 2746

What's the excitation impulse form? Square wave? Why current seems to be raising then - shouldn't it shoot to the max and then fall to zero in a log-like pattern? Are you underdriving the line so hard it takes 250µs to peak excitation voltage? Also I'm curious - can you overdrive the line with TIA o...
by DMA
18 Jul 2016, 16:56
Forum: Workshop
Topic: Anyone has model F 122 key PCB laying around?
Replies: 12
Views: 1373

andrewjoy wrote:
Did you put the spring for the ANSI return and backspace in the right place :P , i have done 3 model F ansi conversions now and i always do it wrong :P
Yep!
But I managed to put two springs to the numpad zero. Not a big deal - just used the original key :)
by DMA
17 Jul 2016, 05:30
Forum: Workshop
Topic: Anyone has model F 122 key PCB laying around?
Replies: 12
Views: 1373

I should have several F122's with the Cindy switch haul on the Model MF project. Would you like me to send you a PCB to test with? wcass already sent me all the photos I need, thanks :) Also I bit the bullet and disassembled mine already. Even managed to assemble it back today - ANSIfied it along t...
by DMA
11 Jul 2016, 03:52
Forum: Workshop
Topic: (Model MF) Remodeling the Model M (aka.. the Mara)
Replies: 2094
Views: 143955

Hmm. I don't think any light would shine through even translucent caps with these switches, unless there were a way to get the light inside the barrels. We'd need glass barrels or something! Maybe phase 2? Drilling extra holes should be nearly free. phosphorglow should know better if it's worth pur...
by DMA
11 Jul 2016, 01:02
Forum: Workshop
Topic: (Model MF) Remodeling the Model M (aka.. the Mara)
Replies: 2094
Views: 143955

Provisions for LEDs under all keys are a good idea. For backlighting if not for nothing else.
This will require keycaps with transclusent inserts to really shine - but even seeing outlines in the dark would be great.
by DMA
08 Jul 2016, 16:31
Forum: Workshop
Topic: [Done] CommonSense: matrix LCR meter with a HID interface
Replies: 569
Views: 62785

Haha... That might be the picture of the year. Too funny. Clever though... Why not It's called "568th of March" in my instagram :) but yeah, all those experiments with "let's try drive those instead of those" led me to a modular solution. That and lots of stuff laying around from the previous offic...
by DMA
08 Jul 2016, 08:14
Forum: Workshop
Topic: [Done] CommonSense: matrix LCR meter with a HID interface
Replies: 569
Views: 62785

Because you're tired soldering and you was The Networking Guy.
568-1.jpg
568-1.jpg (110.05 KiB) Viewed 2068 times
Oh wait, I need that for two keyboards!
Spoiler:
568-reg.jpg
568-reg.jpg (121.8 KiB) Viewed 2068 times
by DMA
07 Jul 2016, 18:29
Forum: Workshop
Topic: (Model MF) Remodeling the Model M (aka.. the Mara)
Replies: 2094
Views: 143955

lot_lizard wrote: I will probably wait a day or two to see if any chimes in with "pink please", and will add a poll to the thread to officially capture.
* Pink
* acid fluorescent green

And, as the crown jewel,
* red with those "racing stripes" and A`PEXi logos tiled all around the plates.
by DMA
07 Jul 2016, 16:58
Forum: Workshop
Topic: (Model MF) Remodeling the Model M (aka.. the Mara)
Replies: 2094
Views: 143955

Something not corroding! Corrosion is a bitch on both of mine :(
by DMA
07 Jul 2016, 01:14
Forum: Workshop
Topic: (Model MF) Remodeling the Model M (aka.. the Mara)
Replies: 2094
Views: 143955

Ratfink wrote: If I had to choose between the two, I guess the scaled lizard would be better as long as there's a vector version of the scale pattern. If you want my complete and honest opinion though, I think they're both pretty cheesy. :mrgreen:
Not cheesier than IBM logo! :)
by DMA
06 Jul 2016, 23:45
Forum: Workshop
Topic: (Model MF) Remodeling the Model M (aka.. the Mara)
Replies: 2094
Views: 143955

Scales are a nice touch, indeed.
by DMA
06 Jul 2016, 06:52
Forum: Workshop
Topic: [Done] CommonSense: matrix LCR meter with a HID interface
Replies: 569
Views: 62785

Unsoldered everything to figure out why the hell the ? key behaves like it does. unsoldered-rotated.jpg backlighted.jpg THE PCB IS PRISTINE. THE FLIPPERS LOOK IDENTICAL. It's mocking me :((( So, at this stage I can't get a working keyboard. Need a second body. I have an XT laying around somewhere th...
by DMA
05 Jul 2016, 21:34
Forum: Workshop
Topic: [Done] CommonSense: matrix LCR meter with a HID interface
Replies: 569
Views: 62785

HuBandiT wrote:
Reverse your scanning direction - does the issue flip sides too?
Huh?
If I understand you correctly, when strobing columns crosstalk only significant between rows(on 122-key) 0-1, 2-3, 4-5, 6-7. Similar both ways.
by DMA
05 Jul 2016, 07:12
Forum: Workshop
Topic: [Done] CommonSense: matrix LCR meter with a HID interface
Replies: 569
Views: 62785

So that you know I'm not abandoned this yet: Spent almost 2 weeks banging me head on the dual-ADC version. Fuck it, not going there. Stashed the, for the lack of a better word, results. Just in case, you know. Back to scanning ADC. Meanwhile had this idea to drive rows and listen at the columns. Sig...
by DMA
01 Jul 2016, 01:00
Forum: Workshop
Topic: [Done] CommonSense: matrix LCR meter with a HID interface
Replies: 569
Views: 62785

Found a bug where I left the sense line untied from the ground. Fixed. It mostly works now. mostly-fine.png There is a problem. It is called "the backspace key". backspace.png The Force is strong in this one. Will try to make pulses shorter and give it time to settle down. Also would be fun to drive...
by DMA
30 Jun 2016, 21:21
Forum: Workshop
Topic: (Model MF) Remodeling the Model M (aka.. the Mara)
Replies: 2094
Views: 143955

Looks really cool!
by DMA
30 Jun 2016, 05:56
Forum: Workshop
Topic: (Model MF) Remodeling the Model M (aka.. the Mara)
Replies: 2094
Views: 143955

I like the idea of putting something between the barrel and PCB. I am also in favor of lifting flippers' feet off the PCB with that "something" - basically leaving the window for the flipper itself. It may also make signal better (It's hard to make it worse - I have pictures in the other thread).
by DMA
29 Jun 2016, 16:35
Forum: Workshop
Topic: [Done] CommonSense: matrix LCR meter with a HID interface
Replies: 569
Views: 62785

$1500 gets you quite a bit of a soldering station. Mine was in the ballpark of $300 with a reasonable collection of tips (6 or 7) and is the best I've ever used (PACE, which I find much better than Weller, Ersa, etc.). I was made aware of jcb yesterday. One of the members of this forum is seriously...
by DMA
29 Jun 2016, 08:51
Forum: Workshop
Topic: [Done] CommonSense: matrix LCR meter with a HID interface
Replies: 569
Views: 62785

I was lucky today. (note: blue stuff goes into the matrix, yellow stuff goes out of it!) I accidentally cheap-o-scope to 50ms (whatever that means. It usually is at 50us at most) and lo! The macroscopic worldview! lucky-optics-1.png Look as the key beautifully flies towards the sense card! lucky-opt...
by DMA
28 Jun 2016, 16:53
Forum: Workshop
Topic: hbar beta, aka hbar's first adventure into Topre land
Replies: 25
Views: 2746

One would still need ADC or at least comparator to use that?
by DMA
27 Jun 2016, 19:39
Forum: Workshop
Topic: hbar beta, aka hbar's first adventure into Topre land
Replies: 25
Views: 2746

hbar, can you please explain to an uneducated person (i.e. me) how TIA works? Or at least point me to the good webpage about that. I am _very_ interested in that "resistance is essentially zero" approach. It looks like it's what IBM does in those square white chips they use in their capacitive keybo...
by DMA
27 Jun 2016, 18:40
Forum: Keyboards
Topic: If you were designing new -- how about a 120% or a 150% keyboard?
Replies: 57
Views: 5243

I suspect some of these chips must be memory chips of some kind. They look too uniform to be processor and communication chips. But the point seems to be that not every keyboard has that kind of internal space to store such a huge PCB that can accommodate a bank of DDRs. Those are buffers. They dri...
by DMA
27 Jun 2016, 03:16
Forum: Workshop
Topic: [Done] CommonSense: matrix LCR meter with a HID interface
Replies: 569
Views: 62785

I'm out of macrocells (whatever that is). And there's no chip with more of those! It looked like this on previous step. singleADC.png It used 40% of macrocells available on the chip. Then I tried to use both ADCs. It escalated quickly - next wanted to push column reading, including pin management, t...
by DMA
25 Jun 2016, 07:04
Forum: Workshop
Topic: [Done] CommonSense: matrix LCR meter with a HID interface
Replies: 569
Views: 62785

I'm writing this post using the === Well, I tried.. after the above line backspace produced all F-keys pressed together :) Anyway. I have good news. The ringing was generated by impedance mismatch between the (driving line + grounded sense line) and the driving pin. After reconfiguring the pins to "...
by DMA
24 Jun 2016, 19:01
Forum: Workshop
Topic: [Done] CommonSense: matrix LCR meter with a HID interface
Replies: 569
Views: 62785

Will this be of help? It's an IBM PC-XT version. I can try to scan the Bigfoot PCB too, if time allows. Thanks, it does help. F122 is different though - it has ground plane on both sides of sense lines. Probably because it's larger. But seeing different examples of the mostly same design allows to ...

Go to advanced search